PSK
31 is a popular digital mode used for transmitting and receiving
text via radio.
My friend, Jeremy Widner, K0PDX has become very effective and
successful with the digital modes, particularly PSK31. Copied
here is a presentation he has offered on the topic.

You can also download this presentation as a Power Point presentation
by clicking here.

The
power in a PSK-31 signal is concentrated in a 31 Hz bandwidth,
versus 250 Hz for RTTY and 3300 Hz for SSB

Transcontinental QSO’s using PSK-31 are possible using
less than 50 W under any conditions and when conditions are
good, QRP (Less Than 5 Watts) PSK-31 contacts are possible to
any point on the planet.

Equipment

Amateur
transceiver that has low frequency drift

Any
modern solid state rig is OK

IC-706
IC-746
TS-940
TS2000
FT-1000
Omni VI

Personal Computer

Most
PSK-31 software is compatible with any version of WindowsSound
card (16 bit Sound Blaster or better) is required